75 research outputs found
Dynamical relativistic corrections to the leptonic decay width of heavy quarkonia
We calculate the dynamical relativistic corrections, originating from
radiative one-gluon-exchange, to the leptonic decay width of heavy quarkonia in
the framework of a covariant formulation of Light-Front Dynamics. Comparison
with the non-relativistic calculations of the leptonic decay width of J=1
charmonium and bottomonium S-ground states shows that relativistic corrections
are large. Most importantly, the calculation of these dynamical relativistic
corrections legitimate a perturbative expansion in , even in the
charmonium sector. This is in contrast with the ongoing belief based on
calculations in the non-relativistic limit. Consequences for the ability of
several phenomenological potential to describe these decays are drawn.Comment: 17 pages, 7 figure
Preon Trinity
We present a new minimal model for the substructure of all known quarks,
leptons and weak gauge bosons, based on only three fundamental and stable
spin-1/2 preons. As a consequence, we predict three new quarks, three new
leptons, and six new vector bosons. One of the new quarks has charge .
The model explains the apparent conservation of three lepton numbers, as well
as the so-called Cabibbo-mixing of the and quarks, and predicts
electromagnetic decays or oscillations between the neutrinos
() and (). Other neutrino oscillations, as well
as rarer quark mixings and CP violation can come about due to a small
quantum-mechanical mixing of two of the preons in the quark and lepton wave
functions.Comment: 5 pages, Latex, no figure
Higgs Pain? Take a Preon!
The Higgs mechanism is the favourite cure for the main problem with
electroweak unification, namely how to reconcile a gauge theory with the need
for massive gauge bosons. This problem does not exist in preon models for quark
and lepton substructure with composite and s, which, consequently,
also avoid all other theoretical complications and paradoxes with the Higgs
mechanism. We present a new, minimal preon model, which explains the family
structure, and predicts several new, heavy quarks, leptons and vector bosons.
Our preons obey a phenomenological supersymmetry, but without so-called squarks
and sleptons, since this SUSY is effective only on the composite scale.Comment: The preon contents of some quarks and leptons have been changed in
order to achieve a more consistent scheme. A few new comments have been
added. 13 pages, LaTeX, no figures. To be published in Proc. of the Meeting
on 'The Fundamental Structure of Matter' and 'Tests of the Electroweak
Symmetry Breaking', Ouranoupolis, Greece, May 199
Non-perturbative renormalization in Light Front Dynamics with Fock space truncation
Within the framework of the Covariant formulation of Light-Front Dynamics, we
develop a general non-perturbative renormalization scheme based on the Fock
decomposition of the state vector and its truncation. The explicit dependence
of our formalism on the orientation of the light front is essential in order to
analyze the structure of the counterterms and bare parameters needed to
renormalize the theory. We present here a general strategy to determine the
dependence of these quantities on the Fock sectors. We apply our formalism to
QED for the two-body (one fermion and one boson) truncation and recover
analytically, without any perturbative expansion, the renormalization of the
electric charge according to the requirements of the Ward Identity.Comment: 7 pages, 6 figures, to appear in the proceedings of the Workshop on
Light-Cone QCD and Nonperturbative Hadron Physics, Cairns, Australia, July
7-15, 200
Preon Prophecies by the Standard Model
The Standard Model of quarks and leptons is, at first sight, nothing but a
set of {\it ad hoc} rules, with no connections, and no clues to their true
background. At a closer look, however, there are many inherent prophecies that
point in the same direction: {\it Compositeness} in terms of three stable
preons.Comment: 13 pages, 8 eps-figures, invited talk at Beyond the Desert '03,
Schloss Ringberg, Bavaria, June 2003; to be published in the Proceeding
Estimates for parameters and characteristics of the confining SU(3)-gluonic field in neutral kaons and chiral limit for pseudoscalar nonet
First part of the paper is devoted to applying the confinement mechanism
proposed earlier by the author to estimate the possible parameters of the
confining SU(3)-gluonic field in neutral kaons. The estimates obtained are
consistent with the widths of the electromagnetic decays
too. The corresponding estimates of the gluon
concentrations, electric and magnetic colour field strengths are also adduced
for the mentioned field at the scales of the mesons under consideration. The
second part of the paper takes into account the results obtained previously by
the author to estimate the purely gluonic contribution to the masses of all the
mesons of pseudoscalar nonet and also to consider a possible relation with a
phenomenological string-like picture of confinement. Finally, the problem of
masses in particle physics is shortly discussed within the framework of
approach to the chiral symmetry breaking in quantum chromodynamics (QCD)
proposed recently by the author.Comment: LaTeX, 16 pages, 2 figure
Linking Geometric Mass Hierarchy with Threefold Family Replication
A link is established between the observed (approximate) geometric mass
hierarchy of quarks and leptons and the triangular structure of their tenable
flavor representations. This singles out SU(3) as the horizontal flavor group,
thereby linking the Fermi mass hierarchy with the threefold family replication.
These linkages are exploited within a flavor-chiral SU(3) model, with fermions
and Higgs bosons in the 3+6* representation. The model is Left-Right symmetric
and utilizes the universal see-saw mechanism with a geometric mass suppression
pattern. Given certain assumptions, the model produces successful mass-ratio
(rather than square-mass-ratio) mixing angle relations and fixes the light
quark mass ratio.Comment: Revtex, 11 twocolumn pages, No figure
Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method
This paper discusses hadron energy reconstruction for the ATLAS barrel
prototype combined calorimeter (consisting of a lead-liquid argon
electromagnetic part and an iron-scintillator hadronic part) in the framework
of the non-parametrical method. The non-parametrical method utilizes only the
known ratios and the electron calibration constants and does not require
the determination of any parameters by a minimization technique. Thus, this
technique lends itself to an easy use in a first level trigger. The
reconstructed mean values of the hadron energies are within of the
true values and the fractional energy resolution is . The value of the ratio
obtained for the electromagnetic compartment of the combined calorimeter is
and agrees with the prediction that for this
electromagnetic calorimeter. Results of a study of the longitudinal hadronic
shower development are also presented. The data have been taken in the H8 beam
line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM
Response of the ATLAS tile calorimeter prototype to muons
A study of high energy muons traversing the ATLAS hadron Tile calorimeter in the barrel region in the energy range between 10 and 300~GeV is presented. Both test beam experimental data and Monte Carlo simulations are given and show good agreement. The Tile calorimeter capability of detecting isolated muons over the above energy range is demonstrated. A signal to background ratio of about 10 is expected for the nominal LHC luminosity (). The photoelectron statistics effect in the muon shape response is shown. The e/mip ratio is found to be ; the e/ ratio is in the range 0.91 - 0.97. The energy loss of a muon in the calorimeter, dominated by the energy lost in the absorber, can be correlated to the energy loss in the active material. This correlation allows one to correct on an event by event basis the muon energy loss in the calorimeter and therefore reduce the low energy tails in the muon momentum distribution
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